Method for improving the bond between glass fibers and elastomeric materials

ABSTRACT

Glass fiber - elastomeric products wherein the glass fiber component is treated prior to combination with elastomeric material with a composition containing a resorcinol formaldehyde resin and one or more elastomeric materials in which the resorcinol formaldehyde resin has been subjected to air oxidation by bubbling air therethrough prior to application onto the glass fiber surfaces.

United States Patent 1191 Marzocchi ,Nov. 27, 1973 METHOD FOR IMPROVINGTHE BOND OTHER PUBLICATION BETWEEN GLASS FIBERS AND G i U t P I O S throgg ns, n1 rocesses n rganic yn esis, ELASTOMERIC MATERIALSMcGraw-l-Iill Book CO., 3rd 1211., (1947), pp. [75] Inventor: AlfredMarzocchi, Cumberland, R.I. 4262427 429 430 [73] Assignee: Owens-CorningFiberglas D Corporation Toledo, Ohio Primary Exammer-W1ll1am D. MartinAssistant Examiner-William H. Schmidt [22] Flled: 1968 Attorney-Staelinand Overman and Herman I. Hersh [21] App]. No.: 780,252

[57] ABSTRACT 52 U.S. Cl 117/126 GB, 117/163 Glass fiber elastomericProducts wherein the glass 51 1111.121 B32b 17/10, B32b 25/10 fibercomponent is treated Prior to Combination with [58] Field f Search H260/846; 117/126 GR elastomeric material with a composition containing a117/163, 126 GB resorcinol formaldehyde resin and one or moreelastomeric materials in which the resorcinol formaldehyde [56]References Cited resin has been subjected to air oxidation by bubblingUNITED STATES PATENTS air therethrough prior to application onto theglass fiber surfaces. 2,902,459 9/1959 Teppema 260/846 X 3,424,6081/1969 Marzocchi et al. 117/126 x 4 Claims, No Drawings METHOD FORIMPROVING THE BOND BETWEEN GLASS FIBERS AND ELASTOMERIC MATERIALS Thisinvention relates to elastomeric products reinforced or otherwisecombined with glass fibers and it relates more particularly to themethod and compositions employed in the treatment of the glass fibers toenhance the bonding relationship between the glass fibers and theelastomeric materials for making fuller utilization of the desirablecharacteristics of the glass fibers in their combination with theelastomeric materials. Y

The term glass fibers, as used herein, shall refer to (1) continuousfibers formed by the rapid attenuation of hundreds of streams of moltenglass and to strands formed when such continuous glass fiber filamentsare gathered together in forming; and to yarns and cords formed byplying and/or twisting a number of strands together, and to woven andnon-woven fabrics which are formed of such glass fiber strands, yarns orcords, and (2) discontinuous fibers formed by high pressure steam or airdirected angularly downwardly onto multiple streams of molten glassissuing from the bottom side of a glass melting bushing and to yarnsthat are formed when such discontinuous fibers are allowed to rain downgravitationally onto a foraminous surface wherein the fibers aregathered together to form a sliver which is drafted into a yarn; and towoven and non-woven fabrics formed of such yarns of discontinuousfibers, and (3) combinations of such continuous and discontinuous fibersin strand, yam, cord and fabrics formed thereof.

As used herein, the term elastomer is meant to include natural rubber inthe cured or uncured stage, vulcanized or unvulcanized stage, andsynthetic organic elastomeric materials such as butadiene-styrenecopolymer, b utadiene-acrylonitrile copolymer, butyl rubber, polysulfiderubbers, EPDM rubbers, chloroprene, isoprene, neoprene, isobutyl rubberand the like elastomeric polymers and copolymers in their cured oruncured stages, and vulcanizedor unvulcanized stages.

The invention is addressed to the fuller utilization of the desirablecharacteristics of glass "fibers, such as their high strength,flexibility, thermal stability, chemical stability, 'inertness,electrical resistance and heat conductive characteristics when used incombinations with elastomeric materials as a reinforcement or as astabilizing agent in belt manufacture, as reinforcing cords and fabricsto increase strength, life, wear-ability, and service characteristics inrubber tires, and as a reinforcement and the like in other elastomericcoated fabrics and molded elastomeric products.

It is an object of this invention to provide a new and improvedcomposition which may be used as a forming size for treatment of glassfibers in forming or preferably as an impregnating composition fortreatment, in forming or afterwards, of bundles, yarns, cords, strandstreatment of bundles, strands, yarns, cords and fabrics of glass fibers,in forming or afterwards, to enhance their bonding relationship whenused in combination with elastomeric materials in the manufacture ofglass fiber reinforced plastics, laminates or coated fabrics and it is arelated object to provide a method and means for making fullerutilization of the strength-properties of glass fibers when used as areinforcement for elastomeric materials.

To the present, glass fibers which have been added or otherwiseincorporated with elastomeric materials, in

1 the form of continuous or chopped fibers, have funcand fabrics formedof glass fibers to enable fuller utili- Y tioned more or less as afiller than as a reinforcement, or flexibilizing agent, or stabilizingagent. As a result, little, if any, improvements in mechanical andphysical properties have been made available from the combinations whichmade use of glass fibers in products fonned of elastomeric materials. Itis believed that the failure to make fuller utilization of some of themore desirable properties of the glass fiber components resides in theinability properly to integrate the glass fibers with the elastomericsystem.

Investigations have been conducted over the past several years by themosthighly skilled in the art in the attempt to make fuller utilizationof the glass fiber components formulated into elastomeric materials inthe endeavor to fabricate products having new and improved physical andmechanical properties. Substantial inroads are now being made asrepresented by the practice of this invention, as will hereinafter bedescribed.

The invention will be described with reference to a new and improvedcomposition which can be employed as an original size applied to theglass fibers in forming thereby individually to coat each of the glassfiber filaments subsequently formed into the strand, yarn, cord orfabric to provide both the desired processing and performancecharacteristics for processing the sized glass fibers in the formationof the strand and in the twisting and plying of the strands into yarnsor cords and in the processing of the strands, yams or cords intofabrics and the desired performance characteristics for enhancing thebonded relationship when the sized glass fibers are combined withelastomeric materials in the.

manufacture of reinforced elastomeric products.

In the preferred practice of this invention, the composition isformulated as an impregnating composition for treatment of strands,yarns, cords and fabrics formed of previously sized glass fibers forpenetration of the treating composition into the strand, yarn, cord orfabric with the intention of individually coating the fibers to protectthe fibers against destruction by mutual abrasion while establishing abonded relationship therewith or else penetrating the glass fiberstrand, yarn, cord or fabric sufficiently to intertie the glass fibersystem with the elastomeric materials with which the glass fibers arecombined in the manufacture of glass fiber elastomeric products.

In the copending application Ser. No. 633,654, filed Mar. 22, 1967 andentitled Glass Fiber Reinforced Elastomers, now US. Pat. No. 3,424,608,description is made of a treating composition in the form of acomposition for sizing individual glass fibers or for impregnatingbundles of glass fibers wherein the treating composition is in the formof an aqueous composition containing as its essential ingredients two to10 parts by weight of a resorcinol formaldehyde resin, six to 20 partsby weight of a butadiene-styrene-vinyl pyridine terpolymer, 12.5 to 20parts by weight of a neoprene rubber and three to nine parts by weightof a butadiene rubber, when used as an impregnating composition, andwhich includes 0.1 to three parts by weight of an anchoring agent in theform of an amino or epoxy silane or an amino or epoxy Werner complexcompound, when used as a size composition.

In the copending application Ser.No. 494,654, filed Oct. 1 1, 1965, andentitled Glass Fiber Size Composition and Products, now abandoned,description is made of a composition for treating glass fibers for useas a glass fiber size or impregnating composition wherein thecomposition is formulated of an aqueous system containing as itsessential ingredients one to six parts by weight resorcinol formaldehyderesin, to 45 parts by weight butadiene-styrene-vinyl pyridineterpolymer, 30 to 60 parts by weight neoprene rubber, three to 12 partsby weight carbon black, when used as an impregnating composition, andwhich includes 0.1 to three parts by weight of an anchoring agent of thetype previously described, when used as a size composition.

In my copending application Ser. No. 398,305, filed Sept. 22, 1964, andentitled Glass Fiber Reinforced Elastomers", now abandoned, descriptionis made of a composition for treating glass fibers as a size or as animpregnant for bundles of glass fibers wherein the treating compositioncomprises an aqueous system having as its essential ingredients,resorcinol formaldehyde resin and a natural rubber latex, when used asan impregnant, and which includes 0.1 to five percent by weight of ananchoring agent of the type described, when used as an impregnant orsize composition.

In the copending application of which I am coapplicant, Ser. No.595,036, entitled Tack-free Impregnated Glass Fiber Reinforcement forElastomeric Materials,now US. Pat. No. 3,567,671, description is made ofa treating composition for use as a size for individual glass fibers oras an impregnant for bundles of glass fibers wherein the treatingcomposition is an aqueous system having as its essential ingredients twoto 10 percent by weight resorcinol formaldehyde resin, to 60 percent byweight butadiene-styrene-vinyl pyridine terpolymer, 15 to 40 percent byweight of a latex of carboxylated butadiene styrene, acrylic resin orvinyl chloride vinylidene chloride resin, and five to percent by weightof an incompatible wax.

It has now been found that when air is bubbled through the resorcinolformaldehyde component of a size or impregnating composition, eitherbefore or preferably after combination with the elastomeric component ofthe size or impregnating composition, the interbonded relationshipbetween the continuous phase elastomer and the glass fiber reinforcementand the compatibility of the glass fiber reinforcement with the matrixof elastomeric material is unexpectedly markedly increased.

It is believed that the exposure to air, prior to the treatment of theglass fibers, effects oxidation of the resorcinol formaldehyde componentwhich tends to enhance interbonding and compatibility with theelastomeric material. There is evidence of the fact that the number ofether, acid and/or aldehyde groups are increased at the expense ofmethylol or formaldehyde groups on the resorcinol formaldehyde resin andthat this may also be a factor in the formation of reactive surfacesthat promote adhesion and enhance compatibility between the treatedglass fibers and the rubber matrix of the product. There is also reasonto believe that double bonds present in the vinylpyridinebutadiene-styrene terpolymer are oxidized to provide groupingscapable of enhancing the bond and interaction with the resorcinolformaldehyde resin as well as the rubber stock during subsequentvulcanization.

As previously pointed out, the described unexpected effect is securedwhen the resorcinol formaldehyde resin is independently processed inaqueous solution or dispersion by bubbling air through the liquid mediumcontaining the same prior to the formulation of the resorcinolformaldehyde resin into the elastomeric materials making up the size orimpregnating composition. However, best results are secured when the airis bubbled through the size or impregnating composition after theresorcinol formaldehyde resin has been formulated with the rubber latexand shortly before application for treatment of the glass fiberreinforcement.

The effect secured is somewhat similar to that of aging glass fiberstreated with resorcinol elastomeric systems before combination with thematrix elastomer for molding the desired glass fiber reinforcedelastomeric product. However, more consistent and better results aresecured by the treatment described and claimed, possibly by reason ofthe reaction through the entire cross-section of the material to suchoxidizing conditions, as distinguished from only the surface exposurethereof in an aging process.

The described improvements in bond and compatibility are observed whenair is bubbled through the resorcinol formaldehyde resin or preferablythe resorcinol formaldehyde rubber latex system for 15 minutes but it ispreferred to bubble air through the material for one-half to 3 hours.When air is bubbled through the system for more than 6 hours, thecompatibility and bond tend to decrease. This is believed to result fromover-oxidation or cure whereby the system becomes less compatible andincapable of effecting the desired interbonding relationship with thecontinuous phase elastomer.

The preferred resorcinol formaldehyde resinous component comprises thecondensation reaction product of 3 mols formaldehyde with 1 mol ofresorcinol with an alkaline medium stabilizer, such as an amine orammonium hydroxide. In order to maintain the alkaline conditions forstabilization during the passage of air through the formed resin, it isdesirable periodically to introduce additional ammonia during the airexposure operation. For this purpose, use can be made of a 5% solutionof ammonium hydroxide.

Suitable resorcinol formaldehyde resins and combinations thereof withnatural rubber latex are marketed by the U. S. Rubber Company under thetrade name Lotol 5440. For the preparation of same, reference can bemade to the Canadian Pat. No. 435,754 issued to the U. S. RubberCompany, in which description is made of the reaction of resorcinol andformaldehyde in the presence of a substantial amount of short chainedalkylamine for purposes of stabilizing the reaction and the productsformed thereof and it also describes the combination of the formed resinwith rubber latex.

Having described the basic concepts of this invention, illustration willnow be made of representative formulations of impregnating and sizecompositions embodying the same.

EXAMPLE 1 impregnating composition: Part A:

732 parts by weight distilled water 1.5 parts by weight ammoniumhydroxide 48 parts by weight resorcinol formaldehyde (42% solids) 1 16parts by weight formalin Part B:

.900 parts by weight butadiene-styrene-vinyl pyridine terpolymer (42%solids) 80 parts by weight ammonium hydroxide 350 parts by weight'carboxylated butadienestyrene latex (50% solids)(Pliolite 480) 50 partsby weight'acrylic resin (50% solids)- (Rhoplex B85) 50 parts by weightVultex Wax No. (56% solids) EXAMPLE 2 Size Composition: 60 parts byweight resorcinol formaldehyde resin (75% by weight solids) 20 parts byweight formalin 1.5 parts by weight sodium hydroxide 900 parts by weightbutadiene-styrene-vinyl pyridine terpolymer (42% solids) 95 parts byweight ammonium hydroxide 350 parts by weight vinyl chloride vinylidenechloride copolymer (50% solids) 200 parts by weight Vultex Wax No. 5(50% solids) 7 parts by weight gamma-aminopropyltriethoxy silane Waterin an amount to reduce the solids content to 1 Part A in Example 1 isseparately prepared by combining the ingredients and then aging forabout 2 to 3 hours with alkali present in amount sufficient to adjustthe pH to between 7 and 7.5. The remainder of the ingredients arecombined and the various parts are then mixed together.

EXAMPLE 3 impregnating Composition: Amount in pounds Water 220 SodiumHydroxide 1 Resorcinol formaldehyde resin (Penacolite Resin R2170 70%solids) 22 Formalin (37% CH O) l5 Ammonium hydroxide (28%) 30 Vinylpyridine terpolymer (Gentac 41% solids) v 250 Neoprene rubber latex (50%solids) 415 Butadiene rubber latex (Pliolite 2104 latex 60% solids) 51Carbon black (Aridye SXN solids) l 15 EXAMPLE 4 Size Composition Partsby weight solids To the foregoing materials water is added to form anaqueous dispersion in amount to provide a solids content within therange of 5 to 20 percent by weight and ammonium hydroxide isincorporated in amount within the range of l to 5 percent by weight, andformalin is added in an amount within the range of 1 to 4 percent byweight for use as a size.

EXAMPLE 5 impregnating Composition:

4080 percent by weight of a natural rubber latex resorcinol formaldehyderesin dispersed in aqueous medium to a solids of 38% by weight 6020percent by weight of water EXAMPLE 6 Size Composition:

15 parts by weight of the natural rubber latex resorcinol formaldehyderesin dispersed in aqueous medium to 38% solids 82 parts by weight ofwater 3 parts by weight of gamma-aminopropyltriethoxy silane EXAMPLE 7impregnating Composition: 2.0 parts by weight resorcinol formaldehyderesin (Penacolite resin R2170 solids) 1.4 parts by weight formaldehyde(37% by weight solution) 5.0 parts by weight concentrated ammoniumhydroxide 25.0 parts by weight vinyl pyridine terpolymer 41% solids(Gentac General Tire & Chemical Comp y) 50.0 parts by weight neoprenerubber latex (50% solids) 7.4 ,parts by weight butadiene latex (Pliolite2104 60% solids) 0.2 part by weight sodium hydroxide 58.0 parts byweight water EXAMPLE 8 Size Composition:

2.0 parts by weight resorcinol fonnaldehyde resin 1.0 parts by weightformaldehyde (37% solution) 2.7 parts by weight concentrated ammoniumhydroxide 25.0-parts by weight vinyl pyridine terpolymer latex (42%solids) 41.0 parts by weight neoprene rubber latex (50% sols ids) 5.0parts by weight butadiene latex (60% solids) .05 part by weight sodiumhydroxide 1.0 part by weight gamma-aminopropyltriethoxy silane 1100parts by weight water in the foregoing examples, the resorcinolformaldehyde resin of Examples 1-4, 7 and 8 and the resorcinolformaldehyde latex component in Examples 5 and 6 are processed prior toformulation with the remainder of the ingredients by -bubbling airthrough the solution for one hour. The treated component is thencombined with the remainder of the ingredients to produce the treatingsize or impregnating composition.

The glass fibers may be sized and the glass fiber bundles may beimpregnated in the conventional manner described in the aforementionedcopending applications. For example, the size compositions may beapplied to the individual glass fibers as they are drawn from the moltenstreams issuing from the bottom side of a glass melting bushing andgathered together to form a yarn.

lmpregnation of a yarn, strand, cord or fabric of glass fibers may bemade by immersing the bundles of glass fibers into a liquid bath of theimpregnating composition after which the excess may be wiped from thesurfaces of the glass fiber bundles and heated to dry and partially curethe impregnated bundles.

When the glass fibers are sized in forming with either of thecompositions, the sized glass fibers can be processed directly intostrand, yarns, cords or fabrics for use in the combination with theelastomeric material without the need for impregnation of the bundlessince the individual fibers in the bundles are already provided with acoating having the desired components for integration with thecontinuous phase elastomeric material and for protecting the glassfibers.

In the combination with the elastomeric materials, the glass fibers orbundles of glass fibers, which are processed in accordance with theprocess of this invention, are mixed with the elastomeric material orotherwise laid down in the desired arrangement for combination with theelastomeric material and processed in the conventional manner bymolding, vulcanization or cure under heat and pressure to advance theelastomeric phase to a cured or vulcanized stage in the combination withthe treated glass fibers whereby the coating or impregnant provided onthe glass fiber surfaces or in the bundles of glass fibers operate tointegrate the continuous phase elastomeric material with the glassfibers whereby the glass fibers become integrated to form a part of theelastomeric product.

Instead of air used in the treatment of the resorcinol formaldehydecomponent of the treating compositions, oxygen or an oxygen containinggas may be bubbled through the liquid composition containing theresorcinol formaldehyde resin.

It will be apparent that l have provided a new and improved compositionfor use in the treatment of glass fibers and bundles formed thereof toenhance the integration and compatibility between the glass fiberreinforcement and the continuous phase elastomeric material in themanufacture of glass fiber elastomeric products.

It will be understood that changes may be made in the details offormulation and operation without departing from the spirit of theinvention especially as defined in the following claims.

I claim:

1. In the treatment of glass fibers for use as reinforcement forelastomeric materials in the manufacture of glass fiber-reinforcedelastomeric products wherein glass fibers, prior to combination withsaid elastomeric materials, when in individual form are coated and whenin bundle form are impregnated, with an alkaline latex containing asessential ingredients a resorcinolformaldehyde resin and one or moreelastomers, the improvement comprising bubbling a molecularoxygencontaining gas through the latex containing theresorcinol-formaldehyde resin under alkaline conditions for a period ofone-fourth to 6 hours.

2. The treatment as claimed in claim 1 in which the oxygen containinggas is air.

3. The treatment as claimed in claim I in which the oxygen containinggas is bubbled through a liquid containing the resorcinol-formaldehyderesin before combination of the resin with the elastomer.

4. The treatment as claimed in claim 1 in which the oxygen containinggas is bubbled through a liquid containing the resorcinol-formaldehyderesin while in admixture with the elastomer.

2. The treatment as claimed in claim 1 in which the oxygen containinggas is air.
 3. The treatment as claimed in claim 1 in which the oxygencontaining gas is bubbled through a liquid containing theresorcinol-formaldehyde resin before combination of the resin with theelastomer.
 4. The treatment as claimed in claim 1 in which the oxygencontaining gas is bubbled through a liquid containing theresorcinol-formaldehyde resin while in admixture with the elastomer.